Dr Loh completed his undergraduate medical education at the University of Glasgow in 1989. His basic surgical training was carried out from 1990 to 1994 on the West of Scotland Surgical training program. During this period, he obtained his Fellowship in general surgery from the Royal College of Physicians and Surgeons of Glasgow.

His paediatric surgical training initially began at the Royal Hospital for Sick Children, Yorkhill, Glasgow in 1994. From here, he went on to do further training at the Royal Victoria Infirmary, Newcastle-upon-Tyne, New Children's Hospital, Westmead, Sydney and the Royal Hospital for Sick Children, Edinburgh.

He obtained the Intercollegiate Fellowship in Paediatric Surgery in March 2002 and completed his post-graduate training in the United Kingdom. He is fully registered as a specialist with the General Medical Council, UK, and the Singapore Medical Council.
He returned to Singapore in August 2002 and joined the department at National University Hospital (NUH). He is currently the Head and Senior Consultant in the department of Paediatric Surgery. He is also an active member of the Paediatric Transplant Programmes at NUH.